Spark-plug



W. C. ROLLINS.

SPARK PLUG.

APPLlcATloN man Aua.2. 19u.

Patented Mar. 9, 1920.

l'rn/etor: Mmmm Cf. Rolling? .E

UNITED sTA'rEs PATENT* orsi ,fi

WEDEN AND ONE-THIRD T0 J. H. SMALLE VVIIIZILIAMI C. ROLLINS, OF MINNEAPOLIS, MINNESOTA, ASSIGNOR 0F ONE-THIRI T0 E. A.

Y, BOTH OF MINNEAPOLS, MNNESOTA.

. SPARK-PLUG.

y Application filed August 2,

Be it known that'I, VILLIAM C. RoLLixs, a citizen of the United States, residing at llinneapolis, in the county ot' Hennepin and State of Minnesota, have invented certain new and uselul Improvements in Spark- Plugs, of which the following is a specification.

My invention relates to spark plugs and has t'or its object to provide a substantially uniilormly cylindrical insulating member which is clamped at its lower edge in a mctallic basel or receptacle against an. annular flange near the end thereof by a cap screwable upon the exterior of said receptacle to almost completely incase said insulating member. .i still further object is to construct the insulator with a cavity on the interior and a spherical projection on the exterior to prevent jumping across of the spark. A still further object is to torm one or more of the spark gap members integral with the receptacle.

The Tull objects and advantages of my invention will appear in connectionwith the detailed-description thereof and are particularly pointed out in the claim.

ln the drawings. illustratingthe application of my invention in one formf- Figure 1 is a side elevational view of the spark plug. Fig. 2 is .an endfview of the same looking toward the spark gap end; Figi'. 3 is a longitiwlinal section taken substantially on line r-IS ot Fig. Q.

My invention which is best shown in Fig. 3 comprises an outer shell or receptacle 10, which is internally bored at 11 to form a shoulder 12 near the extreme end thcreoi'. Within this receptacle is positioned a cylindrical insulator 13 which may be made .ot porcelain or any other suitable insulating material. This insulator' is made hollow at its lowermost extremity l-lleaving a lip 15 extending' completely about the same. At its upper end insulator 13 is formed with a spherical protrusion 16 which extends to within a short distance of the circumference ot the saine torininzgT an annular shoulder 1T. A cap 18 is made serewable upon the end ot the receptacle 10 at 19 and is constructed with a flange portion 20 which engages shoulder 17 of insulator 13 and forces said insulator against a gasket Q1 placed het weon the lip 15 of said insulator and the aforementioned liange I2. This makes a Specification of Letters Patent.

able upon theft end ot said rod.

Patented' Mar. e, ieee.

1917. Serial No. 184,044.

ythe ends of the members 10 and 18 so that the same may be readily picked loose in case of replacement. Again, the gaskets when once loosened almost drop out as they do not have to pass a series of threads as in the ordinary forms.

Through the centerlot.l the insulator runs a rod 23 which serves as one of Le spark gap members and which is held in place at one end by a shoulder Q-l formed thereon which lodges in cavity `14 and ,at the otherend by a lock washer Q5 which rests on protrusion 1G Aand a nut 2G screwthumb nut Q7 serves to hold the lead terminal from. the sparking' system in the usual manner. The other members oll thel spark gap are constructed integral with receptacle 10 as .'lfollows: The interior of the plugrr is bored conical at 2S and 'is turned curved on the exterior at 2f) or turned to any other suitable shape.. The receptzwle 1l) is then mounted in a milling! machine and two parallel` cuts' taken with a cylindrical miller at 8O and 3l as is clearly indicated in Fig: 2. Vlhisleaves two pointed prongs and 33 which approach cach other in the center on opposite sides ot the rod Q55 which is constructed long` enougrh atl u-l to extend beyond the same. lith this construction adjust-- ment ot the gap is hardly necessary as thel portion 3l ot` member Q3 is very short and as the insulator 153 has a long cylindrical portion which will hence tend to centerl itself in the smooth bore of the receptacle 10.

The exterior ot the plug is 'formed with a hexagonal wrench hcad ilo and a fiange 3G and is further threaded at 37 :tor attachment to any of the ordinary torms ot cngines.

The. advantages of my invention are manifest. The device is very simple in construction and effective in operation. Repairs and cleaning can be easily made and due to the self centering ol the insulator only that portion need be removed trom the engine for eleaning'which, greatly simplifies the operation. Breakage or crackage ot the insulator is preventeddue to the uniformity of diameter of the insulator and the relative size or" the same compared to the rest of the plug.

I claim:

A spark plug comprising an outer shell having a uniform bore, an annular flange at one end of the bore, a pair of opposed spark gap members extending toward each other from said flange, an insulating `member fitting within said bore having a lconcave recess at one end whereby a lip is formed at the end of said insulating member adapted to rest upon said fiange. a single spark gap member extending longitudicave recess, and a cap serewable upon the other end of said shell, said cap having an annular Hangeadaptedto engage said insulating member.

In testimony whereof I afix my signature` WILLIAM C. ROLLINS. 

